McC... We had a hen that began staying either on the roost through the day or frequently in a nest box and would come out when we were around. Our hen did it that time because one of the Roos was stalking her! Each time the poor girl went out trying to roam with the rest he would jump her. Poor thing would come running/flying full speed to us and take a flying leap into either our arms or to land on our shoulder when he chased her... he ended up in freezer camp and she came out and roamed freely with the rest after that. If she is missing feathers on her back from the roo he may be fixating on her too much and she feels 'safe' in the box. Maybe get her a hen apron to protect her back because it may be tender also... If it's not rooster induced then I would go with the hormone induced option, she may be 'trying' to go broody and just hasn't committed to it yet.